Land speed measuring instrument



Feb. 28, 1939. T. DE PORTY LANQSPED MEASUMNG INSTRUMENT Filed Fneb. 6, 1937 3 Sheets-Sheet 2 IMH- di l /N VEN rox? E .of ,Do/Q7- THEoPH/L Feb. 28,1939. T, [DE PORT- y 2,148,444

LAND SVPEED MEASURvNG INSTRUMENT Filed Feb. 6, 1957 3 Sheets-het 5 om 7:40 To@ SPR/N6 Ff G /2 Trae/v5 Kr Patented ret. as, rese unirse s'rA'fr-Es sri-inn transom@ mstmmimnir Thcophile de Port, Application February .6,

l. MCaims.

New Carlisle, Ohio i937, Serial No. 124,462

(Granted under the act of March 3, 1883, as amended April 30, 1928: 370 0. G. 757) The invention described herein may bei manufactured and used by or for the Goverment for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to the art of ascertaining the speed of moving bodies and is directed to a novel method and an apparatus for fixing and indicating, at regularly timed intervals upon a surface passed over by a moving body, progresslively spaced points corresponding to instantaneous locations of the moving body relative to.

the said surface in order that the distances between the several indicated points may be measured inascertaining the average speed of the body between successive locations.

The invention is particularly useful in the eld of aeronautics andis herein illustratedand described in connection with its application to an airplane for use in ascertaining the landing speed of the airplane. It is to be understood, however, that the invention is capableof wider application and is intended to be used wherever feasible in determining the speed of any moving body.

Briefly, the apparatus for practicing the method. of the invention consists of a. plurality of gun units suitably mounted on an airplane and Asuccessively and automatically red by a timer mechanism' for discharging specially shaped projectilesfrom the moving airplane into the ground at predetermined constant intervals; there being suitable means provided on the projectiles to facilitate locating same for measuring the distances l between them.

In the accompanying drawings,

AFigure 1 is a top view of the gun-and-rach assembly; l

Figure 2 is a side view thereof, with one of the gun uni-ts in section;`

Figure 3 is an end view of the assembly; Figure 4 is a cross section on line d-i of Figure 2;

Figures 5 and 6 are top and side views, respectively, of the projectile;

Figure '7. is a diagrammatic view of the complete apparatus with a pilot-actuated circuit controlling master switch;

Figure 8 is a schematic showing of the device installed on an airplane, and

Figure 9 -is a View similar to Fig. 8 but showing an automatimswitch in replacement of the pilot-actuated switch.

Figures 10, 1-l and l2 are sectional, detail and schematic views, respectively of an alternate form of the invention.

Any number of gun units may be employed as may be found necessary or desirable. Each gun unit .is composed of an open ended metal tube l externally threaded at one end to receive the internally screw-thread knurled capjor breach 2 and the lock nut v. The breech 2 has a central opening i. Each gunis loaded with a cartridge consisting of a brass shell 5 having a snug ntin the bore of the gun and screwed at its upper 4end into a brass cept; the latter having a flange 'i which overlies the upper edge of the gun barrel. and which isl contacted by an internal shoulder of the breech so as to be clamped to the gun barrel when the breech is screwed down tight. The cartridge cap has a central screw threaded orifice in which is screwed a conventional spark plug 8 which projects outwardly Ithrough the central opening d of the gun breech. The projectile consistsof a specially shaped dart having a tubular shaft 9 of aluminum alloy provided inwardly of an internally beveled extremity l with a head ii and at its other end being provided with fins 2. The head is formed of a selected wood material, such as white pine or spruce, with an approximately hemispherical body from the fiat faced side of which projects a reduced cupped portion with a circular rim I3 of an outside diameterv to have a tight fit in the lower end of the cartridge shell. Rim I3 is spaced inwardly ofthe circular edge of the nat face of the head to providey a shoulder i6 for abutment with the lower edge of the cartridge shell. The head has' a central bore I for insertion of the shaft therethrough and vit is held in position on the shaft by and between two washers it and il, the former being tack' welded to the shaft and the latter being fastened thereto with a cotter i8. As illustrated in Figure 5, two thin plates, preferably of aluminum alloy, are employed to provide the fins i2. These plates are fastened to the shaft, by tack welding, at diametrically opposite points with longitudinal side portions bent angularly asshown to form fins. 'I'he head of the dart forms an abutment for contacting the ground to limit the depth to which the dart penetrates the ground and, together with the exposed position of lthe shaft. and iin, provides visible means for conveniently locating the dart. -Y

The gun units, in vertical position, are supupper and lower'shelf-like anges i9 and 20 at opposite edges of a thin plate body 2l. The top ange i8 has longitudinally spaced screw threadedaholes into which the upper ends ofthe gun barrels are screwed and the bottom flange 2li has corresponding non-threaded openings for receiving the depending lower portions of the gun barrels. The gunbarrels are locked at their screw connections with 'the top liange by means of the lock nuts 3. The body 2| and the bottom flange 20 may consist of a single sheet of mate rial but the top flange I9 i's preferably of separate stock of considerably greater cross section than the body 2l and bottom flange 20 and of greater length than the bottom ange so as to extend appreciably beyond the lvertical side edges of the ported in a metal rack composed of horizontal body, as indicated at 22', for convenient attachment to a support; the extensions-22 having aperture 33 through which they may be bolted or otherwise fastened to the support. In addition, each flange is provided on its upper surface with a pair of short open ended metal tubes 24 which are welded to the flanges. The top ange is also secured, by Welding to the upper edge of the rack body 2|.

The gun barrels are of greater length than the cartridges and projectiles and the projectile is held in the cartridge casing by friction with a wadding 25 and an explosive charge 26 at its inner end. The explosive charge may be ignited in various ways and means for accomplishing this electrically is illustrated in Figure 7 which illustrates an arrangement of electrical circuits such as are generally employed in a conventional battery ignition system. The primary circuit consists of a battery 21, primary winding 28 of an induction coil, contact breaker or timer mechanism 29 and master switch 36. The secondary circuit includes the secondary winding 3l, distributor 32 and spark plug 8. As is well understood in the art, the mutual induction in the secondary winding on the interruption of the primary circuit, when the contacts 33 of the timer mechanism are opened by the mechanically operated timer cam 34, results in a high-induced E. M. F. which is suilicient to produce, through the distributor circuit, a spark at the gap of the spark plug corresponding to the particular distributor segment 35 with which the distributor arm or brush 36 is at such time in contact. The timer cam 34 and the insulated distributor arm 36 are mounted on a common shaft for rotation at uniform speed so that the primary circuit will be opened and closed at predetermined intervals for successive ring of the gun units. The means (not shown) for imparting rotation to the arm and cam of the distributor-timerv mechanism may be a constant-speed spring-Wound motor or a constant speed electric motor with proper gearing and aknown rotational velocity.

In practice, the device is suitably installed crosswise in an airplane fuselage with the muzzles of the guns directed downwardly so that the darts are shot into the ground and the timing mechanism is set in operation'just before the airplane (the landing speed of which is to be measured) is nosed down for a landing. At the instant when the. speed of the airplane in level ight over the ground is desired to be known, the pilot closes the switch 30 of the primary circuit so that the darts or markers successively discharged into the' ground from the gun barrels indicate on the ground passed over by the airplane instantaneous vlocations of the latter at the time of the discharges. By knowing the interval between successive iiring of the gun barrels and the measured distance between discharged markers on the ground, the average speed at which the airplane was traveling between the successive shots can be accurately determined.

The embodiment of the invention illustrated in Figure 9 differs from the previouslyv'described structure merely in the substitution of an' automatic switch for the pilot-operated switch 30. IIhis automatic switch consists of an elongated bar or lever 31 fulcrumed at 38 to provide a short upper arm and a long lower arm. The upper arm of the lever, which is of insulating material, carries a contact point 39' which is electrically connected with one end of the primary circuit and the lower arm of the lever is made heavy or weighted at its lower end 40 to normally position the lever inclusive, corresponds to the previously described in Figure 7, for igniting the same.

with the contact point 33 spaced from a stationary contact point 4|, which is electrically connected with the other end of the primary circuit. The'lever ispreferably installed in the airplane at a point rearwardly adjacent the landing gear so that in the normal position ofthe lever, the lower end of the same extends downwardly below the landing wheels. Hence, when the airplane is close to the ground in making a landing the lower end of the lever contacts the ground 1 before the landing wheels are grounded and is turned about its axis to engage contacts 39 and 4l at the instant the landing wheels are grounded; the engagement of the contacts closing the primary circuit and causing a marker to be dlsl charged from a gun barrel at the instant of landing and at intervals while the airplane is rolling along the ground.

The modification disclosed in Figures 10 to 12,

device except that the conventional spark plug 6 is replaced by an electric match-detonator 42 which does not require a booster such as shown The current passes directly from the source 43 to the dls- 2 tributor 44 and thence to the selected electric match detonator which may be of any well known and conventional construction.

Having thus described the invention, I claim:

1. A device for use in ascertaining the speed of a a moving body comprising downwardly directed projectile-discharging means carried by the body and armed with dart shaped projectiles to be successively discharged into the ground at predetermined intervalsl while the body is in motion, 3

- means provided on said projectiles in order to locate same on the ground for measuring the distances between them, and means for actuating the projectile-discharging means to discharge the projectiles successively and at predetermined constant intervals.

2. A device i'or use in ascertaining the speed of a moving body relative to the ground passed over] comprising a plurality of guns mounted on said f body and directed groundward, a charge in each 4 gun consisting of an -explosive and an arrow-like projectile, an electrical firing circuit including a distributor and a timer for causing said guns to be med-consecutively and at known constant intervening intervals to cause the projectiles to be discharged into the ground to indicate thereon instantaneous locations of the moving body at the times ofthe discharges.

3. A-'device for use in ascertaining the landing 5 speed of an airplane which consists of a plurality of guns mounted on the airplane and directed downwardly for discharging into the ground, a charge in each gun consisting of an explosive and a dart type projectile, means for ring said a guns to cause said projectiles to be shot intothe ground successively and at predetermined intervening intervals While the airplane is in motion to indicate on the ground instantaneous locations of the airplane at the times of the discharges, ci said means consisting of an electric ignition circuit of the jump spark type and a normally opened circuit closer having an operating arm depending from the airplane for contact with the ground before the landing gear of the airplane 74 is grounded when making a landing, said arm being responsive to such contact for closing the ignition circuit substantially at the instant the landing gear is grounded for causing a marker to be discharged at the instant oflanding and at 71 intervals while the airplane is rolling along the ground. .4. A device for establishing on the ground xed points representing successive distances passed 5 over by an airplane in known equal units of time for convenient `measurement of such distances to ascertain the average speed ofthe airplane between successive points which comprises the combination with an airplane of a plurality of' .0 guns directed downwardly for discharging'into the surface of the ground, a charge in each gun v consisting of an explosive and a dart-shaped projectile having a slender tubular shaft provided inwardly of Iits ground-penetrating end with an L5 abutment for limiting the depth to which the projectile penetrates the ground; and automatic means for ring said gunsto discharge the said projectiles successively and at predetermined inscrewed at their upper ends into the openings on the upper ange and depending at their lower 30 ends through corresponding openings in the lower ange, a screw cap on the upper end 'of each tube, a cartridge in each tube having a supporting flange at its detonator end adapted to rest 'upon the upper edgel of the tube and to be clamped g5 to the latter by the said screw cap, the latter having a central opening through which the detonator end of the cartridge is-exposed.

6. In a device of the character described, a gun barrel/ consisting of\a `tube and a breech cap l having a central opening; a cartridge consisting of a tubular 'shell vhaving a snug iit in the bore of the tube-and a cartridge cap screwed o'ver the rear end of the shell, said cartridge cap having a supporting. flange extending between the edge s \of the gun tubefand the breech cap to be clamped to the tube when the said cap isscrewed down thereon, a spark plug screwed in said cartridge cap 'and extending outwardly of the gun tube through the central opening in the breech cap; a dart projectile in sadfcartridge shell consisting of a slender shaft having an innerl feathered end v -and an outer headed end-in yfrictional sustaining contact with the internal wall of the shell; and

a wadding and an explosive charge atthe inner 55 end of the projectile.

'7.'A dart comprising a slender shaft having a.

feathered end and a target-penetrating end, and an abutment-forming member xed on the said shaft in slightly set back relation to the target- 50 penetrating end of the shaft and extending laterally of the shaft for contacting the target to limit the depth to which the dart may penetrate thearound the latter in slightly set back relation to the chamferedend of the tube for contacting 7o the target to limit the depth to which dart may penetrate the target.

9. A um comprime-sienes: shaft naviera leasable objects carried by nlsm.

feathered end and a target-penetrating end, and a hemispherical head Axeri on the said shaft in slightly set back relation to the target-penetrating end of the shaft and withits rounded surface forwardlydisposed for contacting the target to 5' limit the depth to which the dart may penetrate the target.

10. A dart having a slender shaft feathered at one end, a pair of relatively spaced washers encircling the shaft adjacent the opposite end of 10 the latter, the trailing washer being rigidly connected with the said shaft and the leading washerbeing releasedly connectedvwith the shaft for removal therefrom, and a removable head having a centrally apertured body Lembracing the shaft and secured thereto by and between the said washers.

11. A dart having a slender shaft provided with a feathered end and a target-penetrating end, a

pair of relatively spaced washers mounted on the said shaft in set back relation to the target-penetrating end of the shaft,- the washer farthest removed from thesaid target-penetratipg end of the shaft being welded to the-shaft and the other washer being fastened to the shaft with a cotter, and a head mounted on the shaft and held in fixed position thereon-by and-between theI said washers to provide an abutment for contacting the target to limit the depth to which the dart.

may penetrate the target. 30 12. In a cartridge, a cartridge shell containing an explosive charge and a projectile, the said projectile consisting of a hemispherical head disposed outwardly of the shell with its at faced side disposed against the forward edge of the shell 85 and provided with a reduced portion having a tight friction it in the forward end of the shell, a

vslendershaft flxed at its outer end to the said head and extending inwardly and centrally of the said shell Ifrom a point externally beyond the said headand shell, and a plurality of-ns integral with the inner end of the shaft and extending radially therefrom into frictional contact with, the surrounding wall ofthe shell.

13. The method of ascertaining the velocity of a moving vehicle relative to-the'surface passed over which consists -in marking the surface at known constant time intervals'and at places thereon corresponding to instantaneous locations of the vehicle at the time of the marking to 5o I establish flxed points representing successive distances passed over by the vehicle in known equal units of time, and then measuring the. distances between the xed points to evaluate the distance factor D in the equation V=D/T,'.where "13 repre'- 55 sents the time and V represents the velocity.

14. A device for use in ascertaining the landing speed of Van airplane which comprises the cembination wth'the airplane of a pluralityof re.

adapted when released to fallito the ground and to remain xed eiative .thereto as reference points for measurig purposes, normally inactive automatic mechanism operable forreleasing the r said .objects singly and at known constant time intervals,l and means mounted on the airplane for contacting the` ground shortly prior to the instant of landing and responsive to such .contact for initiating the operation of the releasing mecha-1,

nn PORT.

the airplane and 

